Marco has opened #889668 to just install the .service and the .timer
file at the correct location but not enabling them by default.

I can live with that.

I'll try to see if I can provide a patch.

I guess that it would be a good compromise for now, I also think that
putting these file in an example directory is a bit meh.
But I'm seeing something weird, all my disks on my laptops have the
"discard" option set but for some reasons when running "fstrim -v -a"
it
still says that had trim data on all the FS.
Do I miss something?

Do you have an encrypted root filesystem? Or LVM? You need to take additional
steps to enable discard if so.

For LVM there is AFAIK nothing to do, the TRIM operation are passed to
the next layer by default, the only option in the config is to generate
TRIM when changing the size of a LV.

For the cryptsetup/Luks level, I'm passing the discard option in the
crypttab.

I just tried on my desktop at home (simple LVM without encryption) and I
can see the same thing behavior.